Insulating material

ABSTRACT

An insulating material is constructed in weight percent from about 20-60% low melt bicomponent fiber, 10-40% high melt bicomponent fiber and 20-60% staple fiber. The material provides a unique combination of strength, acoustical insulating and even thermal insulating properties heretofore unavailable in the art.

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION

[0001] The present invention relates generally to the field ofacoustical and thermal insulation and, more particularly, to a uniquenew insulating material of low-melt and high-melt bicomponent fibersexhibiting a unique blend of structural and acoustical insulatingproperties.

BACKGROUND OF THE INVENTION

[0002] Acoustical and thermal liners for application to vehicles arewell known in the art. These liners typically rely upon both soundabsorption, i.e. the ability to absorb incident sound waves andtransmission loss, i.e. the ability to reflect incident sound waves, inorder to provide sound attenuation. They also rely upon thermalshielding properties to prevent or reduce the transmission of heat fromvarious heat sources (e.g. engine, transmission and exhaust system), tothe passenger compartment of the vehicle. Such insulation is commonlyemployed as a hoodliner, dash liner and firewall liner. More recently,such liners have been employed on engine covers so as to attenuate thesound of the engine closer to its source.

[0003] Examples of acoustical and thermal insulation in the form ofliners are disclosed in a number of prior art patents including U.S.Pat. Nos. 4,851,283 to Holtrop et al. and 6,008,149 to Copperwheat. Asshould be apparent from a review of these two patents, engineers havegenerally found it necessary to construct such liners from a laminateincorporating (a) one or more layers to provide the desired acousticaland thermal insulating properties and (b) one or more additional layersto provide the desire mechanical strength properties which allow simpleand convenient installation as well as proper functional performanceover a long service life.

[0004] While a number of adhesives, adhesive webs and binding fibershave been specifically developed over the years to secure the variouslayers of the laminates together, laminated liners and insulators havean inherent risk of delamination and failure. The potential is, in fact,significant mainly due to the harsh operating environment to which suchliners and insulators are subjected. Many liners and insulators arelocated near and/or are designed to shield high heat sources such as theengine, transmission and components of the exhaust system. As a result,the liners and insulators are often subjected to temperatures in excessof 200° F. which have a tendency to degrade the adhesives or bindersover time.

[0005] Additionally, many liners and insulators are subjected to waterfrom the surface of the roadways which has a tendency to be drawn bycapillary action into the interface between the layers of the liner orinsulator. Such water may have a deleterious affect upon the integrityof the adhesive layer over time. This is particularly true when thatwater includes in solution salt or other chemicals from the roadwaywhich are corrosive and destructive.

[0006] A need is therefore identified for a hood, dash, firewall orengine cover liner incorporating a nonlaminate acoustical and thermalinsulating layer of polymer fibers which avoids any inherent potentialfor delamination. Such a liner is suitable for use in the hightemperature operating environment of the engine compartment and capableof providing the desired mechanical strength and rigidity for ease ofinstallation as well as the desired acoustical and thermal insulatingproperties.

SUMMARY OF THE INVENTION

[0007] Accordingly, the present invention relates to an insulatingmaterial exhibiting a unique combination of acoustical insulating andstrength/structural properties. The insulating material comprises inweight percent from about 20-60% low melt bicomponent fiber, 10-40% highmelt bicomponent fiber and 20-60% staple fiber. The melt includes anaverage fiber diameter of between about 10-30 microns, more typically16-24 microns and most typically 18-22 microns. The material has adensity of between about 1.0-10.0 pcf and a flexural strength of betweenabout 40-1200 psi. Still more specifically describing the invention, theinsulating material has the acoustical absorption coefficients asfollows: 0.17-0.24 at a frequency of 500 Hz, 0.29-0.63 at a frequency of1000 Hz, 0.50-0.94 at a frequency of 2000 Hz and 0.71-0.99 at afrequency of 4000 Hz all at 2 pcf density.

[0008] Still further describing the invention, the insulating materialhas a thermal conductivity value of between about 0.20 and 0.30 at 2 pcfdensity. The staple or bulking fibers are selected from a group ofmaterials consisting of polyester fibers, polyethylene fibers,polypropylene fibers, nylon fibers, rayon fibers, glass fibers, naturalfibers and mixtures thereof.

[0009] The low melt bicomponent fibers are selected from a group ofmaterials consisting of copolyester/polyethylene terephthalate(CoPET/PET), poly 1,4 cyclohexanedimethyl terephthalate/polyethyleneterephthalate (PCT/PET), poly 1,4 cyclohexanedimethylterephthalate/polypropylene (PCT/PP), glycol-modified polyethyleneterephthalate/polyethylene terephthalate (PETG/PET),propylene/polyethylene terephthalate (PP/PET), nylon 6/nylon 66,polyethylene/glass, or other combinations of polymers includingpolymer/glass and polymer/natural fiber that yield differential meltflow temperatures. The bicomponent fibers may be any of a variety ofconfigurations that yield acceptable fiber binding such as sheath-core,side-by-side, segmented pie, etc. The low melt bicomponent fibers aredescribed as having a melt flow temperature of about 100 to 130° C.

[0010] The high melt bicomponent fibers are selected from a group ofmaterials consisting of copolyester/polyethylene terephthalate(CoPET/PET), poly 1,4 cyclohexanedimethyl terephthalate/polyethyleneterephthalate (PCT/PET), poly 1,4 cyclohexanedimethylterephthalate/polypropylene (PCT/PP), glycol-modified polyethyleneterephthalate/polyethylene terephthalate (PETG/PET),propylene/polyethylene terephthalate (PP/PET), nylon 6/nylon 66, orother combinations of polymers that yield differential melt flowtemperatures. The bicomponent fibers may be any of a variety ofconfigurations that yield acceptable fiber binding such as sheath-core,side-by-side, splitable segmented pie, etc. The high melt bicomponent isdescribed as having a melt flow temperature of about 170-200° C.Bicomponent fibers described as crystalline or semi-crystalline whichhave a melt flow temperature of generally about 150 to 180° C. may besubstituted in part or whole for the high melt bicomponent fiber.

BRIEF DESCRIPTION OF THE DRAWING

[0011] The accompanying drawing incorporated in and forming a part ofthe specification, illustrates several aspects of the present invention,and together with the description serves to explain the principles ofthe invention. In the drawing:

[0012]FIG. 1 is a schematical side elevational view of one possibleembodiment of the present invention;

[0013] FIGS. 2-4 are schematical side elevational illustrations of otherpossible alternative embodiments of the present invention;

[0014]FIG. 5 is a graphical illustration comparing the flexural strengthin the machine direction of the structural/acoustical insulatingmaterial of the present invention with a standard state of the artpolymer formulation; and

[0015]FIG. 6 is a graphical illustration comparing the flexural strengthin the cross machine direction of the structural/acoustical insulatingmaterial of the present invention with a standard state of the artpolymer formulation.

[0016] Reference will now be made in detail to the present preferredembodiment of the invention, an example of which is illustrated in theaccompanying drawing.

DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention relates to an insulating material that isparticularly noteworthy for its combination of structural and acousticalproperties. Specifically, as described below the insulating materialyields at least a 100% improvement in elastic modulus over a standardpolymer formulation while (1) maintaining equivalent acoustics to thestandard formulation, (2) yielding high temperature performance and (3)having a minimal cost upcharge over standard formulations. While in thepast it has generally been found necessary to give up a significantlevel of acoustical performance or utilize much higher priced fibers orboth to gain improvement in structural properties, the present inventionachieves the dramatic increase in elastic modulus without compromisingacoustical properties or low production costs and as such represents asignificant advance in the art.

[0018] The insulating material of the present invention comprises inweight percent from about 20-60% low melt bicomponent fiber, 10-40% highmelt bicomponent fiber and 20-60% staple fiber. The melt includes anaverage fiber diameter of between about 10-30 microns, or typically16-24 microns and most typically 18-22 microns. The material has adensity of between about 1.0-10.0 pcf and a flexural strength of betweenabout 40-1200 psi.

[0019] For purposes of clarity, the bicomponent fibers are comprised ofa principal polymer component and a binder polymer component. Thebicomponent fibers may be formed as sheath-core fibers with theprincipal polymer component forming the core material and the binderpolymer component forming the sheath around the core. It should beunderstood, however, that other arrangements may be utilized such as aside-by-side arrangement. In any such arrangement, the binder polymercomponent binds the bicomponent fibers and the staple fibers tothemselves and to each other.

[0020] The binder polymer component of the bicomponent fibers has asoftening point lower than the softening point of the principal polymercomponent so that the two materials respond differently upon heating.When heated to a temperature above the softening point of the binderpolymer component but below the softening temperature of the principalpolymer component, the binder component softens and becomes sticky,thereby bonding the various bicomponent fibers where they are in contactwith each other and the staple fibers. As long as the temperature is notraised as high as the softening point of the principal polymercomponent, that component remains in the form of fibers.

[0021] The low melt bicomponent fibers are selected from a group ofmaterials consisting of copolyester/polyethylene terephthalate(CoPET/PET), poly 1,4 cyclohexanedimethyl terephthalate/polyethyleneterephthalate (PCT/PET), poly 1,4 cyclohexanedimethylterephthalate/polypropylene (PCT/PP), glycol-modified polyethyleneterephthalate/polyethylene terephthalate (PETG/PET),propylene/polyethylene terephthalate (PP/PET), nylon 6/nylon 66,polyethylene/glass, or other combinations of polymers includingpolymer/glass and polymer/natural fiber that yield differential meltflow temperatures. The bicomponent fibers may be any of a variety ofconfigurations that yield acceptable fiber binding such as sheath-core,side-by-side, segmented pie, etc. The low melt bicomponent fibers aredescribed as having a melt flow temperature of about 100 to 130° C.

[0022] The high melt bicomponent fibers are selected from a group ofmaterials consisting of copolyester/polyethylene terephthalate(CoPET/PET), poly 1,4 cyclohexanedimethyl terephthalate/polyethyleneterephthalate (PCT/PET), poly 1,4 cyclohexanedimethylterephthalate/polypropylene (PCT/PP), glycol-modified polyethyleneterephthalate/polyethylene terephthalate (PETG/PET),propylene/polyethylene terephthalate (PP/PET), nylon 6/nylon 66, orother combinations of polymers that yield differential melt flowtemperatures. The bicomponent fibers may be any of a variety ofconfigurations that yield acceptable fiber binding such as sheath-core,side-by-side, splitable segmented pie, etc. The high melt bicomponent isdescribed as having a melt flow temperature of about 170-200° C.Bicomponent fibers described as crystalline or semi-crystalline whichhave a melt flow temperature of generally about 150 to 180° C. may besubstituted in part or whole for the high melt bicomponent fiber.

[0023] The insulating material provides unique acoustical insulatingproperties in combination with the flexural strength of between about40-1200 psi. Specifically, the insulating material is characterized byacoustical absorption coefficients of 0.17-0.24 at a frequency of 500Hz, 0.29-0.63 at a frequency of 1000 Hz, 0.50-0.94 at a frequency of2000 Hz and 0.71-0.99 at a frequency of 4000 Hz all at 2 pcf density.The insulating material also has a thermal conductivity value of betweenabout 0.20 and 0.30 at 2 pcf density. Accordingly, it should beappreciated that the insulating material also provides good thermalinsulating properties in conjunction with good acoustical insulating andstructural properties.

[0024] The staple or bulking fibers utilized in the insulating materialare selected from a group of materials consisting of polyester fibers,polyethylene fibers, polypropylene fibers, nylon fibers, rayon fibers,glass fibers, natural fibers and mixtures thereof.

[0025] The insulating material of the present invention may be utilizedfor a number of applications requiring the unique structural, acousticalinsulating and, when appropriate for certain applications, thermalinsulating properties of the present invention. For example, theinsulating material of the present invention may be utilized in theconstruction of hood, dash, firewall or engine cover liners such asshown in FIGS. 1-4 of the present invention.

[0026] The liner 10 shown in FIG. 1 comprises an acoustical and thermalinsulating layer 12 of the insulating material of the present invention.More specifically, a single, nonlaminated layer 12 is provided with thenecessary mechanical strength and rigidity to allow easy installationand the desired acoustical and thermal insulating properties.Advantageously, all of these benefits are achieved in a light weightliner 10 which may even be used in compact vehicles where fuel economyconcerns lead manufacturers to seek weight savings wherever possible.

[0027] In a first alternative embodiment shown in FIG. 2, the liner 10also comprises a single, nonlaminated acoustical and thermal insulatinglayer 12 of the insulating material of the present invention. The layer12 includes a relatively high density, nonlaminate or unitary skin 14 ofthat insulating material along at least one face thereof. The formationof the relatively high density, nonlaminate skin 14 of polymer fiber maybe completed in accordance with the process described in detail inco-pending U.S. patent application Ser. No. 09/607,478, entitled“Process For Forming A Multi-Layer, Multi-Density Composite Insulator”,filed Jun. 30, 2000 (Owens Corning Case Nos. 24811 and 24812). The fulldisclosure of this document is incorporated herein by reference.

[0028] Advantageously, the high density skin 14 will not delaminate fromthe layer 12 under the environmental conditions existing in the enginecompartment and also adds structural integrity and strength to the liner10 which aids significantly in handling and fitting the part duringinstallation. The high density skin 14 is also more aestheticallypleasing. Still further, for many applications the high density skin 14eliminates the need to provide an additional facing layer of anothertype of fabric material. This serves to virtually eliminate anypotential for failure of the lining due to delamination. It also resultsin a liner 10 made exclusively of one material that is, therefore, fullyrecyclable.

[0029] Further, since the skin may be formed with a hot platen duringthe molding of the liner 10 to its desired shape, no additionalprocessing step is required. This reduces production costs relative to aliner with a fabric or other facing since such a facing must be adhereto the acoustical and thermal insulating layer in a separate processingstep.

[0030] In yet another embodiment shown in FIG. 3, the liner 10 includesa single, nonlaminated acoustical and thermal insulating layer 12 of theinsulating material of the present invention in combination with afacing layer 16 over a first face 18 of the acoustical and thermalinsulating layer. The facing layer 16 may be constructed from a polymermaterial selected from a group consisting of polyester, rayon,polyethylene, polypropylene, ethylene vinyl acetate, polyvinyl chlorideand mixtures thereof.

[0031] In yet another alternative embodiment shown in FIG. 4, the liner10 comprises a single, nonlaminated acoustical and thermal insulatinglayer 12 of the insulating material of the present invention asdescribed above in combination with a first facing layer 16 covering afirst face 18 thereof and a second facing layer 20 covering a second,opposite face 22 thereof. The second facing layer 20 may be constructedfrom the same or a different material as the first facing layer 16.Preferably the first and second facing layers have a weight of betweenabout 0.50-3.00 ounces per square yard.

[0032] In accordance with yet another aspect of the present invention,the acoustical and thermal insulating layer 12 may be a natural white orinclude any appropriate form of coloring or pigment in order to providea gray or black color. Alternatively, the acoustical and thermalinsulating layer 12 may incorporate any appropriate color or pigment soas to substantially approximate the color of the first and/or secondfacing layers 16, 20 and/or the paint color of the vehicle. Thisprovides significant aesthetic benefits. Specifically, when the liner 10is molded under heat and pressure in order to nest with the hood,firewall or other appropriate body panel or superstructure of the enginecompartment, the liner 10 is often subjected to deep drawing at one ormore points. This deep drawing has a tendency to spread the weave of thefabric facing 16, 20 thereby exposing a portion of the underlying face18, 20 of the acoustical and thermal insulating layer to light. If theacoustical and thermal insulating layer 12 does not substantially matchthe color of the facing layer 16, 20 this creates an undesirable colorvariation in these deep drawn areas. In contrast, by matching the colorof the layer 12 with the facings 16, 20, this color variation may besubstantially eliminated.

[0033] It should further be appreciated that during use the facing layer16, 20 may become snagged or subjected to a partial tear exposing someof the face of the underlying acoustical and thermal insulating layer12. Once again, by matching the color of the layer 12 with the facing16, 20, any color variation is substantially eliminated and one'sattention is not as readily drawn to the damaged area. Accordingly, anoverall improved aesthetic appearance is maintained over the servicelife of the liner 10.

[0034] The insulating material of the present invention is produced inaccordance with processing steps generally known in the art.

[0035] The fibers need to be blended in the given ratios and thermallybonded to form a semi-rigid blanket. The fibers generally are packagedin 500-700 lb. bales. Each of the three fibers is generally baledseparately although it is possible to get the fibers from the fibersupplier blended in the proper ratio and baled together. For purposes ofthis description, it is assumed that the fibers come baled separately.Generally each baled fiber needs to be “opened” by a bale opening systemcommon in the industry. The opening system fluffs up the fiber and sendsthe appropriate amount of fiber by weight to a blending area. Thisfluffing serves to decouple the clustered fibrous masses and enhancesfiber-to-fiber contact. The blending area distributes the differentfibers uniformly according to the desired fiber ratios.

[0036] Once blended the fibers are uniformly distributed on a conveyingsystem forming an unbonded “sheet” or “blanket” of uniformly distributedfibers. Thermally activated powdered binders or other supplementalbinding methods may be added during the fiber blending or conveyingstages prior to the sheet entering the thermal bonding oven. The oven isconstructed to allow heated air to penetrate the fibrous pack and bringthe fibers to a temperature sufficient to activate the binding fibersand/or other binding materials. If the blanket material is beingproduced for post molding applications, the oven temperature need onlybe high enough to activate at least some of the low melt binding fibers.The post mold operation only needs to reach temperatures high enough toactivate the higher melt fibers. If no post mold operation is to occurthen the oven needs to be set to a temperature high enough to activateboth the low melt and high melt fibers—in this case the requiredtemperature would be at least 180° C. Once the fibers have reached theappropriate temperature the oven or post oven area should be capable ofreducing the temperature below the activation point of the bindingmaterials, in this case approximately below 100° C. The desiredthickness of the blanket is generally established in the oven process.After exiting the oven, additional binding materials such as powders canbe added to the fibrous blanket or other treatments such as densifyingone or both surfaces of the blanket can occur.

[0037] The blanket can now be handled and utilized “as is” forstructural-acoustical applications or it can be post molded to produceparts of simple or highly complex shapes. Molding methods can vary amongthose typically used in the industry for molding of thermoplasticmaterials. One such method is to preheat the blanket material to asufficient temperature to (re)activate all of the binding materials andthen quickly transfer the heated blanket to a cold molding tool andpress mold the part until the temperature of the fibers are below theactivation point of the low melt binding fibers.

[0038] In the case of the samples used for structural testing in thefollowing example, no post molding operation was utilized to achieve thedesired test thickness.

[0039] The following examples are presented to further illustrate theinvention, but it is not to be considered as limited thereto.

EXAMPLE

[0040] The structural/acoustical formulation for the insulating materialof the present invention was tested and compared to a standardformulation of 40% low melt bicomponent having an average fiber diameterof 14.3 microns, 30% staple (bulking) fiber having an average fiberdiameter of 12.4 microns and 30% staple (bulking) fiber having anaverage fiber diameter of 50.0 microns. Together, the standardformulation had an average fiber diameter of 30.0 microns. Flexuralstrength testing of the structural/acoustical formulation of theinsulating material of the present invention and the standardformulation was then run in accordance with ASTM D1037 static threepoint bend. The results of this testing are clearly illustrated in FIGS.5 and 6. FIG. 5 shows the flexural strength of the two formulations inthe machine direction and FIG. 6 shows the flexural strength of the twoformulation in the cross-machine direction. In both instances, it shouldbe appreciated that the structural/acoustical formulation of theinsulating material of the present invention provides at least a 100%improvement in elastic modulus over the standard formulation tested.

[0041] The structural/acoustical formulation of the insulating materialof the present invention also provides acoustical absorptioncoefficients somewhat better than those provided by the standardformulation and as such, provides significant gains in strength andenhanced acoustical insulating performance. As such, the presentinvention represents a significant advance in the art.

[0042] In summary, numerous benefits result from employing the conceptsof the present invention. An insulating material providing a uniquecombination of structural strength, acoustical insulating and eventhermal insulating properties is provided. The insulating material isparticularly suited for use as a hood, dash, firewall or engine coverliner. It provides the mechanical strength and rigidity to allow ease inhandling and installation while also providing thermal and acousticalinsulating properties that are consistently and reliably maintained overa long service life even in the high temperature and high moistureoperating environment of the engine compartment. Such performancecharacteristics have heretofore been unavailable in a linerincorporating a single, nonlaminated layer of acoustical and thermalinsulating material.

[0043] The foregoing description of a preferred embodiment of theinvention has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed.

[0044] The embodiment was chosen and described to provide the bestillustration of the principles of the invention and its practicalapplication to thereby enable one of ordinary skill in the art toutilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. Forexample, crystalline/semicrystalline bicomponent fibers having a meltflow temperature of about 150° C. to about 180° C. may be substituted inwhole or in part for the high melt bicomponent fiber. All suchmodifications and variations are within the scope of the invention asdetermined by the appended claims when interpreted in accordance withthe breadth to which they are fairly, legally and equitably entitled.

What is claimed
 1. An insulating material, comprising in weight percentabout 20-60% low melt bicomponent fiber, 10-40% high melt bicomponentfiber and 20-60% staple fiber.
 2. The material of claim 1, including anaverage fiber diameter of between about 10-30 microns.
 3. The materialof claim 1, including an average fiber diameter of between about 16-24microns.
 4. The material of claim 1, including an average fiber diameterof between about 18-22 microns.
 5. The material of claim 1, wherein saidmaterial has a density of between about 1.0-10.0 pcf and a flexuralstrength of between about 40-1200 psi.
 6. The material of claim 5,wherein said material has the acoustical absorption coefficients asfollows: freq (Hz) @ 2 pcf density  500 0.17-0.24 1000 0.29-0.63 20000.50-0.94 4000 0.71-0.99


7. The material of claim 6, wherein said material has a thermalconductivity value of between about 0.20 and 0.30 at 2 pcf density. 8.The material of claim 1, wherein said low melt and high melt bicomponentfibers are a concentric sheath/core CoPET/PET.
 9. The material of claim8, wherein said staple fibers are selected from a group of materialsconsisting of polyester fibers, polyethylene fibers, polypropylenefibers, nylon fibers, rayon fibers, glass fibers, natural fibers andmixtures thereof.
 10. The material of claim 1, wherein said material hasthe acoustical absorption coefficients as follows: freq (Hz) @ 2 pcfdensity  500 0.17-0.24 1000 0.29-0.63 2000 0.50-0.94 4000 0.71-0.99


11. The material of claim 10, wherein said material has a thermalconductivity value of between about 0.20 and 0.30 at 2 pcf density. 12.The material of claim 11, wherein said staple fibers are selected from agroup of materials consisting of polyester fibers, polyethylene fibers,polypropylene fibers, nylon fibers, rayon fibers, glass fibers, naturalfibers and mixtures thereof.
 13. The material of claim 1, wherein saidstaple fibers are selected from a group of materials consisting ofpolyester fibers, polyethylene fibers, polypropylene fibers, nylonfibers, rayon fibers, glass fibers, natural fibers and mixtures thereof.14. The material of claim 13, wherein said low melt bicomponent fibersare selected from a group of materials consisting ofcopolyester/polyethylene terephthalate, poly 1,4 cyclohexanedimethylterephthalate/polyethylene terephthalate, poly 1,4 cyclohexanedimethylterephthalate/polypropylene, glycol-modified polyethyleneterephthalate/polyethylene terephthalate, propylene/polyethyleneterephthalate, nylon 6/nylon 66, polyethylene/glass, polymer/naturalfibers and mixtures thereof that yield differential melt flowtemperatures.
 15. The material of claim 14, wherein said bicomponentfibers are in a configuration selected from a group consisting ofsheath-core, side-by-side, segmented pie and mixtures thereof.
 16. Thematerial of claim 14, wherein said low melt bicomponent fibers have amelt flow temperature of about 100 to about 130° C.
 17. The material ofclaim 13, wherein said high melt bicomponent fibers are selected from agroup of materials consisting of copolyester/polyethylene terephthalate,poly 1,4 cyclohexanedimethyl terephthalate/polyethylene terephthalate,poly 1,4 cyclohexanedimethyl terephthalate/polypropylene,glycol-modified polyethylene terephthalate/polyethylene terephthalate,propylene/polyethylene terephthalate, nylon 6/nylon 66, and mixturesthereof that yield differential melt flow temperatures.
 18. The materialof claim 17, wherein said high melt bicomponent fibers are in aconfiguration selected from a group consisting of sheath-core,side-by-side, splitable segmented pie and mixtures thereof.
 19. Thematerial of claim 17, wherein said high melt bicomponent fibers have amelt flow temperature of about 170 to about 200° C.
 20. The material ofclaim 17, wherein crystalline/semicrystalline bicomponent fibers havinga melt flow temperature of about 150 to about 180° C. are substituted inpart or whole for said high melt bicomponent fiber.